What is Landing page?

A page specifically designed for a prospect to land on after clicking a call to action in an email, ad, or other channel, with a single focus on driving one conversion action such as a lead, sale, download, or signup.

From How to Create Landing Pages That Convert Sponsored by SE Ranking Ep. 539

A page built to target a specific keyword or small set of keywords, ensuring visitors who click through from search results find content directly relevant to their search.

From Internet Marketing - Google Local Process - Unknown Secrets to SEO E-Webstyle Number 3

Any page on a site that ranks, receives traffic, and is built to convert visitors through purpose, messaging, visual appeal, a goal, and a call to action.

From How to Make Every Web Page an Awesome Landing Page by Stoney deGeyter #314

A specific page a user arrives on after clicking an ad, which should be focused on one product or offer, match the user demographic, and include a clear call to action.

From Landing Page Design Tips - #seopodcast 214

A destination page a PPC ad links to. It must contain the keywords and information the user searched for, and it should be integrated into the website rather than standing alone to rank well and reduce click costs.

From Facebook Places and a Great PPC Campaign - Unknown Secrets of SEO E-Webstyle Number 72